The present invention relates to a pressing assembly. In particular, although not exclusively, the invention relates to a pressing assembly which includes a loading/unloading means to convey bales into a column-type press. However, the invention is not restricted in its use for conveying bales into a press and may indeed be adapted or applied to convey any type of object into any type of press.
Conventional presses used for pressing bales are column-type presses. These presses include two opposing platens moveable relative to one another to press a bale between the opposing faces of the platens. A number of columns extend between the two platens, the number usually being four with the columns symmetrically arranged on either side of the press. The considerable stresses associated with the pressing force are transferred through the columns. Therefore the bale should be presented accurately to the press. Any misalignment could cause serious imbalance to the columns, the likely result being cracking of the press columns or the frame of the press.
Conventionally, bales are presented to the press by an endless belt conveyer. The belt runs over the top of one of the platens defining the press table and down through an opening under the table. The inherit difficulty with this arrangement is that as a bale is compressed by the press, this action tends to stretch the belt and so cause rapid wearing of the belt. If the belt joint should lie within the press during pressing, considerable stress will be placed on the joint. This leads to inevitable breaking of the belt involving substantial down time while a new belt is fitted and tracked.
It is therefore an object of the present invention to provide a pressing assembly and/or a method of pressing which overcomes or ameliorates the disadvantages referred to above or provides the public with a useful choice.
In accordance with a broad aspect of the present invention there is provided a pressing assembly including a press being moveable from an open configuration to an operable configuration to compress an object, and a loading means having one or more pushers moveable into a region within the press to load the object to a pressing zone within the press, the arrangement being such that the or each pusher is clear of the pressing zone once the press is in the operable configuration.
Preferably there are two pushers arranged to act on opposite sides of the object. The pushers may be retractable to move past a subsequent object to be loaded. Preferably the assembly also includes ejection means.
In accordance with a second aspect of the present invention there is provided a pressing assembly including a press for pressing objects, a loading/unloading means for loading objects into and out of the press, the loading means including a reciprocable pusher assembly moveable in a forward and a reverse direction, the pusher assembly having a first pusher moveable with the pusher assembly for loading one of said objects to a pressing zone in the press on forward movement of the pusher assembly, a second pusher moveable with the pusher assembly for ejecting another of said objects from the pressing zone on forward movement of the pusher assembly wherein, in the reverse direction of the pusher assembly, the second pusher is moveable to retract beyond the object loaded into the pressing zone.
Preferably the reciprocal pusher assembly includes a linkage enabling the first and second pushers to move in unison. It is preferred that the linkage is a rail. This construction enables the rail to slide linearly along a support frame. The linkage, eg the rail, with the first and second pushers may be disposed to the side of the path of objects being loaded into the press.
Suitably the reciprocal pusher assembly is such to load objects one by one into the press. Alternatively, bundles or groups of objects may be loaded into the press although the preferred intended application is for use with pulp bales.
In a most preferred form of the invention there are two rails disposed on either side of the path of the objects being loaded into the press, each including first and second pushers. It is preferred that the two rails are joined so as to move in unison thereby defining a moveable carriage. This enables the carriage to be reciprocated by a single reciprocating means such as an hydraulic cylinder.
As mentioned above, the preferred means of moving the reciprocable pusher assembly is by an hydraulic cylinder. However, other arrangements eg using cams, rack and pinion are also considered within the scope of the present invention.
As mentioned above, the reciprocable pusher assembly may be slidable relative to a support frame. In a preferred form of the invention this includes a track with gliders extending from the reciprocable pusher assembly received within the track. The support frame may be erected independently next to the press. Alternatively, one end of the support frame may be supported by the press.
Preferably, the press includes opposing horizontal platens moveable relative to one another. Suitably, but not exclusively, one platen is stationary while the other moves. The base of the objects it transverses the path through the loading/unloading means towards the press defines a loading plane. Preferably, the stationary platen is level with the loading plane. Suitably, the press operates to close in a direction orthogonal to the loading plane. The press is preferably a column type press.
Suitably, the reciprocable pusher assembly is such that it does not interfere with the operation of the press during the closing of the platens. The reciprocable pusher assembly may be completely free of the platens prior to any closing of the press. Alternatively, the press may operate to initially apply a minimal pressure to the object within the press to thereby hold the object in the pressing zone so as to minimise the possibility of movement when the reciprocable pusher assembly is moved in the reverse direction. The reciprocable pusher assembly may move into the space between the opposing platens once the platens have opened sufficiently to enable a subsequent object to be loaded into the press. Alternatively, the reciprocable pusher assembly may be completely free of the press until the platens are fully open.
The second pusher operating as an ejection pusher may be pivotable. In an alternative form of the invention, the second pusher may simply reciprocate for example at 90xc2x0 to the direction of movement of the reciprocable pusher assembly. For example, a reciprocable pusher may include a curved surface which, when making contact with an object in the pressing zone cause the pusher to retract inwardly. As another alternative, rollers may be incorporated to assist with retraction of the second pusher.
In a most preferred form of the invention, there are two second pushers on either side of the path of the objects moving towards the press each being elongate in the form of fingers.
Preferably, the second ejection pushers are biased to return to the unretracted configuration once past the pressing zone to return the second pushers to a configuration adapted to eject an object from the press. A spring may form a suitable bias to the second pusher.
The pusher may be moveable to retract out of the pressing zone by simple contact with the object in the pressing zone. For this reason, it is preferred that the biasing means biasing the second pusher to the unretracted configuration has a lesser effect than the force resisting movement of the object from the pressing zone. This will ensure that the second pusher does not inadvertently disturb the object in the pressing zone on its reverse movement with the reciprocable pusher assembly. In an alternative form of the invention, the second pusher may be tripped to automatically retract when moving past the pressing zone.
Preferably the first pusher moves an object from a loading zone to the pressing zone. In a similar fashion to the second pusher, the first pusher may be moveable relative to the reciprocable pusher assembly during the reverse direction of the pusher assembly, to retract beyond the loading zone. The first pusher may therefore possess any of the features described above in connection with the second pusher.
The pressing assembly further includes a conveying means to convey objects to the loading zone. The conveying means may be aligned with the loading plane along which the objects move on their path to the press. In an alternative form of the invention, the conveying means may convey the objects from above or below or from either side. Preferably the conveying means is a belt conveyer.
In accordance with a third broad aspect of the present invention there is provided a method of loading objects into a press having two opposing platens, the method including using one or more pushers to load the object to a pressing zone within the press whereby the pushers are clear of the pressing zone once the press operates to compress the object.
In accordance with a fourth aspect of the present invention there is provided a method of loading/unloading objects into a press, the method including using a reciprocable pusher assembly having first and second pushers, moving the reciprocable pusher assembly in a forward direction to simultaneously move both the first and second pushers such that the first pusher moves one of said objects to a pressing zone in the press and the second pusher ejects another of said objects from the press, moving the reciprocable pusher assembly in a reverse direction to simultaneously move both the first and second pushers wherein the second pusher also moves to retract beyond the pressing zone.
This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.
The invention consists in the foregoing and also envisages constructions of which the following gives examples only.